In a vehicle side air bag device described in Patent Document 1, a side air bag includes: a rear-side tube bag portion configured to extend in an up-down direction on a vehicle rear side relative to an outer end, in a vehicle width direction, of a chest of a sitting occupant at the time when the side air bag is expanded and unfolded; and a front-side tube bag portion placed on a vehicle front side relative to the rear-side tube bag portion and on the vehicle rear side relative to the outer end, in the vehicle width direction, of the chest of the sitting occupant and configured to extend in the up-down direction. An upper part of the rear-side tube bag portion is placed on a lateral side of a shoulder of the sitting occupant so as to serve as a shoulder restraining portion that restrains the shoulder, and an upper edge of the front-side tube bag is placed at a position lower than a side of the sitting occupant on the vehicle front side relative to the shoulder restraining portion, and serves as an arm support portion on which an upper arm of the sitting occupant is placed.
That is, in the vehicle side air bag device, that shoulder of the sitting occupant which has a relatively high resistance is restrained by the shoulder restraining portion, while the upper arm of the sitting occupant is placed on the arm support portion, so as to prevent the upper arm from being placed between an air bag and that chest of the sitting occupant which has a relatively low resistance.